7 Pole standard Commercial Vehicle HGV To 13 Pole Passenger Car Socket Voltage Reducing Interconnector 24v to 12v . Designed to enable recovery of trailers and caravans fitted with a 12v supply without the need for fitting a rear lighting board. This product provides automatic voltage reduction from a 24v supply from the recovery vehicle to 12v output on the trailer or caravan and enables full operation of the trailer / caravan rear light clusters, also allowing full connectivity to any multi-pin socket fitted to the recovery vehicle. The most commonly fitted sockets to HGV vehicles are 7 Pole Commercial HGV; 7 Pole passenger Vehicle; 13 Pole (Scheduled for introduction late 2008).